Safety-switch



M. H. SHOENBERG.

SAFETY SWITCH.

APPLICATION FILED 050.27, 1919.

Patented Oct. 11, 1921.

INVENTOR m y ATTORNEYS tions under the action of a snap spring from the switch member from and break To an whom a may sitions of the .u m mm PATENT,

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, concern:

Be it known that I, MmnoN H SHOEN- BERG, a citizen of the United States and a resident of the city and county of San Francisco, State of California, have invented new and useful Improvements in Safety- Switches, 01 which the following is a specification. My invention has for its object the automatic interruption of an electric circuit, when the current flowing in the apparatus and supplied through my safety switch for any reason exceeds a predetermined amount, and at the same time, the switch may be closed or opened manually, but in the event of such closure the circuit will be immediately automatically interrupted the event of this excess flow of current; furthermore, it is impossible with my invention to retain the flow of current beyond the limits of safety by any possible hand manipulation of the switch. These objects I attain by providing a movable switch blade, or blades, which ma e swung into either of two extreme POSI- a suitable finger member, and in either of its extreme positions the switch is open while in its intermediate position able switch and while in such position is under the control of an expansion element or thermostat wire in series with the flowing current.

The current which is caused to flow upon the closure of the switch and flowing through the thermostat wireraises the temperature thereof, results in the expansion of the wire, which operates the aforesaid latch, releasing its intermediate position, and causing it to snap in one or the other direction, depending u on the position of the finger member. ese extreme positions corresponding with the open -poswitch result in the interruption of the current flow. l

- It is to be specially noted that the make at the switch-contacts always occur very quickly and under the action of a spring,.protecti the parts against discharge damage. urthermore, as the expanslon of the thermostat element is exactly coincident with the temperature raise of the said element, the switch is instantly and automatically opened by any excess current within extremely wide range without damage to the parts, and the terminal apthe mov- -member completes the circuit, f

This latter is perforated on Specification of Letters Patent. Patentd oct. 11,1921... Application med December 27,1919. Serial No. 347,739,. I

. By referring to, the accompanying draw- 6 1n s my invention will be made clear.

lgurel is an enlarged view of my switch arranged in conjunction with the standard form of socket. Th

and forms no part of my invention.

Fig; 2 is a side view at right angles to F1 1 and to a reduced'scale. I ig. 3 is a side view similar to Fig. 2 but from the opposite side thereof. p

Fig.4 is a side view similar to Fi 2, except that the fin er piece and switc blade is shown in a difigrent position. Fig. 5 is the same as Fig. 2 and Fig. 4, except the switch blade and shown in another position.

Fig. 6 is a di gram of the connections thereto.

Fig. 7 is a cross section lated base and socket stat element therein.

Fig. 8 is a detail'showing of the latch 21 and its electrical connections and associated parts.

through the insuer to similar parts.

The switch parts are mounted on an insulated member indicated by the numeral 1, supported on a suitable base 2, carrying also a connecting piece or standard socket 3.

At 4 is a U shaped member carried upon the supporting pivot 5, which fpivot passes through enlarg d holes 6, 6 o the switch blade 15, and on the end of the said pivot I mount the operating finger he movement of the key 9'causes a cone sponding movement of the U member 4. its end for the bar is pivoted,

passage of the bar 10, which at 11 to the second .U member 12-, to which 100 is rigidly attached the side arms 13, 14 with wh1ch are mounted the switch blades 15, 16

through insulated connections 17, 17, 17, 17 so that the members 15 and 16 are preferabl insulated from the I structure, except when incontact with circuit terminals. f

Around the-bar 10 is assembled-the coil spring 18 under compressiom'which acts u on the second U piece corresponding switch blades in one direction or the other 15 16 to -sw1ng depending upon e housing "is not shown 1n the figures as 1t is well known'in the art finger piece are showing the thermo-,80

Throughout the figures like numerals repiece or key 9. Q5

balance of the switc 12, to cause it andt e the position of the U piece 4, and therefore upon the operation of the key or fin erpiece 9. It will be obvious that if the piece 4 be turned into its up position, the s ring 18 will tend to throw the switch bla es to one extreme or limit, and if the U piece 4 be turned into the down position the spring will tend to throw the switch blades to the opposite limit.

The limits of said movement are elther the surface 19 or 20,or the latch member 21, the latter serving as limit of movement only for the switch blades when the U piece 4 is turned to its upper position. The said latch 21 is under the control of an expansion element, or thermostat wire 22 (see Fig. 7) which wire terminates in the button 23, and is held in tension by the coil spring 24.

Cooperating with the latch 21 1s a llght spring 25, lightly holdmg the said latch against the button 23. I prefer to connect the button 23 with the circuit terminal 31 by the flexible strip 27 to insure an electrical connection.

The upper part of the switch blade 16 I provide with a tongue, or .projectlng lug 28, adapted to engage with the said latch 21 when the thermostat wire 22 is in its contracted position admitting of the latch en.- gaging the said lug. The main circuit wires are connected to terminals 29', 30 from which the current is conveyed upon the closing of the switch and the engagement of the switch blade at 28 with the latch 21 through the switch blades 16 and 15, iece 27 and wire 22, by which the current 1s conveyed to the socket and button 26, the other le being connected to the socket shell 3 througn a connection 33, and contact terminal 32.

The operation is as follows:

Assuming that a lamp of normal wattage, for which the apparatus has been previously designed and constructed, be connected into the socket 3, and that the switch parts are in the position shown in Fig. 5, the key 9 is now to be turned so that the U piece '4 is forced downward into the position shown in Fig. 4, which will result in the switch blades 15, 16 turning into the position there shown, dur-in which the projecting lug 28 will have passed under the tripping end of the latch 21. The key is now turned back in the 0pposite or on direction when the U piece 4 is turned into the position indicated in Fig. 2; this will cause the switch blades 15,

16 to snap into the position there shown, and to be retained in such position by the latch 21 during normal current consumption. Current will now flow to the lamp socket and the lamp will be energized, the current therefor flowing also through the wire 22 in series therewith. Said current is not, however, sufiicient to heat the wire 22 and ex- I pand it beyond the predetermined range, and

amassa consequently latch 21 is not raised sufii-- ciently to release the lug 2830f the switch blades. The light may be turned on and of! as often as required by merely shifting the key 9 when the switch blades will occupy the position of closed in Fig. 2, or open in Fig. 4, as the case may be. Should, however, a

short circuit occur, or any load in excess of 5.- lierein'made to my co-pendcember 27 1919, wherein is set forth a further showing of certain features of my inventibn. I

Claims.

- 1. In an electrical safety switch, an oscillating member adapted to snap about a central pivot into each of two extreme positions under the action of a spring, a spring con structed and adapted to cause said move ment on either side of said pivotal means on a reverse movement of the opposite end of said spring, contacting blades constructed and adapted to engage said member when the member is in its intermediate position, said blades constructed and adapted to complete a circuit through the blades and the member, latch means adapted to retain the member in said intermediate position when swinging from one end of its range of movement, associated means controlling said latch adapted to actuate to release the said latch upon an excess of current flowing through said blades and switch member.

2. In an electrical safety switch, an oscillating member adapted to snap about a central pivot into each of two extreme positions under the action'of a spring, a spring constructed and adapted to cause said move ment on either side of said pivotal means on a reverse movement of the opposite end of said spring, contacting blades constructed and adapted to engage said member when the member is in its intermediate position, said blades constructed and adapted to complete a circuit through the blades and the member, latch means adapted to retain the member in said intermediate position when swinging from one end of its range of movement, associated means controllin said latch adapted to actuate to release t e said .latch upon an excess of current flowing through said blades and switch member, in-

eluding an expansible element in series with said blades and member adapted to ex and upon the excess of current flowing therethrough and releasing said latch whereby under the action of a spring, a spring conthe member snaps into open circuit position structed and adapted to cause said moveunder the action of the spring. ment on either side of said pivotal means 3. In an electrical safety switch, an oscilon a reverse movement of the opposite end lating member adapted to snap about a cenof said spring, contacting blades constructed tral pivot into each of two extreme posiand adapted to engage said member when tions under the action of a spring, a spring the member is in its intermediate position, constructed and adapted to cause said movesaid blades constructed and adapted to comment on. either side of said pivotal means plete a circuit through the blades and the on a reverse movement of the opposite end member, latch means adapted to retain the of said spring, contacting blades constructed member in said intermediate position when and adapted to engage said member when swinging from one end of its range of movethe member is in its intermediate position, ment, associated means controlling said said blades constructed and adapted to comlatch adapted to actuate to release the said plete a circuit through the blades and the latch upon an excess of current flowin member, latch means adapted to retain the through said blades and switch member, inmember in said intermediate position when eluding an expansible element in series with swinging from one end of its range of 'movesaid blades and member adapted to expand ment, associated means controlling said upon the excess of current flowing therelatch adapted to actuate to release the said through and releasing said latch whereby latch upon an excess of current flowing ,the member snaps into open circuit position through said blades and switch member, inunder the action of the spring, said expansieluding an expansible element in series with ble element secured to a supporting frame said blades and member adapted to expand on the end opposite to said latch, and a upon the excess of current flowing therespring adapted to force the tension of said through and releasing said latch whereby expansible wire, and a button at the termithe member snaps into open circuit position nation of'said wire, and a relatively lighter under the action of the spring, said expa-nsispring retaining said latch in contact with ble element secured to a supporting frame said button. on the end opposite to said latch. In testimony whereof, I have hereunto set 4, In an electrical safety switch, an oscilmy hand at the city and county of San Franlating member adapted to snap about a cencisco, State of California. tral pivot into each of two extreme positions MILTON H. SHOENBERG. 

